I have three Surface Tablets with Windows 10 that all have the same problem.
When I try to copy a file over wifi, the copy file dialog window sits at 0% and "Calculating" forever.
The workaround is to refresh the destination folder in Windows Explorer (right-click in folder>refresh).

I would like to fix whatever is causing this issue.
What I know:
All the surface tablets can get out to the internet with good speeds.
This issue does not occur on my Surface Pro 2 with Windows 8.
This issue did not occur on my Surface Pro 3 with Windows 8
This issue does occur on my Surface Pro 3 after upgrading to Windows 10.
This issue does occur on my Surface Pro 4 with Windows 10.
This is not a problem on various other Windows 10 laptops connected to the same Wifi.
There is ample hard drive space for the copy operation. (5TBs available for a 47MB file)
The file transfer happens successfully, but the window never shows it and will sit there forever.
Trying to close or cancel the window freezes the Surface for several minutes and never works.
Refreshing the destination folder (a network drive) on the Surface tablet is the only way to get it to stop "Calculating".
Please assist. This is incredibly frustrating. It took me weeks to figure out the workaround and I can't find any help about this issue.